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    SubjectRe: [PATCH 6/7] s390: vfio-ap: handle dynamic config/deconfig of AP adapter
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    On 11/04/2019 23:03, Tony Krowiak wrote:
    > Once an APQN is assigned to an mdev device it will remained assigned until
    > it is explicitly unassigned from the mdev device. The associated AP queue
    > devices, however, can come and go due to failures or deliberate actions by
    > a sysadmin. For example, a sysadmin can dynamically remove an AP adapter
    > card using the SE or by executing an SCLP command. This patch refactors
    > the probe and remove callbacks of the vfio_ap driver to handle dynamic
    > changes as follows:
    >
    > * Probe callback changes:
    >
    > If the APQN of the queue being probed is assigned to an mdev device, the
    > mdev device is in use by a guest, and the APQN is not set in the guest's
    > CRYCB, the CRYCB will be dynamically updated to give the guest access to
    > the queue.
    >
    > * Remove callback changes:
    >
    > If the APQN of the queue being removed is assigned to an mdev device,
    > the mdev
    > device is in use by a guest, and the APQN is set in the guest's CRYCB,
    > the CRYCB will be dynamically updated to remove the guest's access to
    > the adapter card associated with the queue. Keep in mind, the
    > architecture does not provide a way to remove access to a single queue
    > unless only one queue is in the guest's configuration, so it was decided
    > that it makes more sense to unplug the adapter from the guest.
    >
    > The APQN of the queue being removed will remain assigned to the mdev
    > device should the queue be dynamically returned to the configuration.
    > The queue will also be reset prior to returning control to the caller
    > (a.k.a., the AP bus).
    >
    > Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
    > ---
    > arch/s390/include/asm/kvm_host.h | 2 ++
    > arch/s390/kvm/kvm-s390.c | 37 +++++++++++++++++++
    > drivers/s390/crypto/vfio_ap_drv.c | 16 +++++++--
    > drivers/s390/crypto/vfio_ap_ops.c | 67 +++++++++++++++++++++++++++++++++--
    > drivers/s390/crypto/vfio_ap_private.h | 2 ++
    > 5 files changed, 120 insertions(+), 4 deletions(-)
    >
    > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
    > index c47e22bba87f..0ce5d9b0df59 100644kvm_s390_crypto_cb
    > --- a/arch/s390/include/asm/kvm_host.h
    > +++ b/arch/s390/include/asm/kvm_host.h
    > @@ -895,6 +895,8 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
    > void kvm_arch_crypto_clear_masks(struct kvm *kvm);
    > void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
    > unsigned long *aqm, unsigned long *adm);
    > +int kvm_arch_crypto_test_masks(struct kvm *kvm, unsigned long *apm,
    > + unsigned long *aqm, unsigned long *adm);
    >
    > extern int sie64a(struct kvm_s390_sie_block *, u64 *);
    > extern char sie_exit;
    > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
    > index 4638303ba6a8..5f423cdd29ba 100644
    > --- a/arch/s390/kvm/kvm-s390.c
    > +++ b/arch/s390/kvm/kvm-s390.c
    > @@ -2217,6 +2217,43 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm)
    > kvm->arch.crypto.crycbd |= CRYCB_FORMAT1;
    > }
    >

    This function requires the big matrix lock, may be add a comment.

    > +int kvm_arch_crypto_test_masks(struct kvm *kvm, unsigned long *apm,
    > + unsigned long *aqm, unsigned long *adm)
    > +{
    > + int ret;
    > + struct kvm_s390_crypto_cb *crycb = kvm->arch.crypto.crycb;
    > +
    > + switch (kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK) {
    > + case CRYCB_FORMAT2: /* APCB1 use 256 bits */
    > + ret = bitmap_equal(apm, (unsigned long *)crycb->apcb1.apm, 256);
    > + VM_EVENT(kvm, 3, "TEST CRYCB: apm %016lx %016lx %016lx %016lx",
    > + apm[0], apm[1], apm[2], apm[3]);
    > + ret &= bitmap_equal(aqm,
    > + (unsigned long *)crycb->apcb1.aqm, 256);
    > + VM_EVENT(kvm, 3, "TEST CRYCB: aqm %016lx %016lx %016lx %016lx",
    > + aqm[0], aqm[1], aqm[2], aqm[3]);
    > + ret &= bitmap_equal(adm,
    > + (unsigned long *)crycb->apcb1.adm, 256);
    > + VM_EVENT(kvm, 3, "TEST CRYCB: adm %016lx %016lx %016lx %016lx",
    > + adm[0], adm[1], adm[2], adm[3]);
    > + break;
    > + case CRYCB_FORMAT1:
    > + case CRYCB_FORMAT0: /* Fall through both use APCB0 */
    > + ret = bitmap_equal(apm, (unsigned long *)crycb->apcb1.apm, 64);
    > + ret &= bitmap_equal(aqm, (unsigned long *)crycb->apcb1.aqm, 16);
    > + ret &= bitmap_equal(adm, (unsigned long *)crycb->apcb1.adm, 16);
    > + VM_EVENT(kvm, 3, "TEST CRYCB: apm %016lx aqm %04x adm %04x",
    > + apm[0], *((unsigned short *)aqm),
    > + *((unsigned short *)adm));
    > + break;
    > + default: /* Can not happen */
    > + ret = 0;
    > + break;
    > + }
    > + return ret;
    > +}
    > +EXPORT_SYMBOL_GPL(kvm_arch_crypto_test_masks);

    Wouldn't it be interesting to work on the ap_matrix structure instead of
    on the real CRYCB?
    You could spare a lot of tests and wouldn't require to change this file.

    Regards,
    Pierre


    --
    Pierre Morel
    Linux/KVM/QEMU in Böblingen - Germany

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